From six to zero per cent Mycobacterium avium subsp. paratuberculosis milk ELISA positivity in three years - probably...

Area of Science:

• Veterinary immunology
• Microbiology
• Animal health

Background:

• Paratuberculosis (Johne's disease) is a chronic intestinal infection in ruminants.
• Current control methods for paratuberculosis are often costly and time-consuming.
• Mycobacterium vaccae possesses immunomodulatory properties that may enhance host defense.

Purpose of the Study:

• To evaluate the efficacy of live Mycobacterium vaccae administration in reducing paratuberculosis carriage in a dairy herd.
• To assess the impact of M. vaccae on Mycobacterium avium subspecies paratuberculosis (MAP) shedding.
• To determine if M. vaccae can serve as an alternative control strategy for paratuberculosis.

Main Methods:

• Administered live M. vaccae (10^10 bacteria) via gavage to newborn heifers within 24 hours of birth and again 2 weeks later.
• Monitored paratuberculosis herd status annually using milk ELISA.
• Assessed fecal MAP shedding in 3-year-old cows using qPCR, comparing treated animals to controls.

Main Results:

• Milk ELISA positivity decreased from 6% to 0% within 3 years in the treated herd.
• Only 1% of treated cows tested positive for MAP shedding via qPCR, compared to 2.46% in control animals.
• Two of three positive control animals later tested negative, while the persistently positive control cow continued shedding MAP.

Conclusions:

• Live M. vaccae administration shows promise as an inexpensive and rapid method for paratuberculosis control in dairy cattle.
• Further research is warranted to explore the potential of M. vaccae as a viable alternative to existing paratuberculosis management strategies.
• Heifer-to-cow transmission of M. vaccae may play a role in its propagation within the herd.